BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

exponent challenge

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Newbie | Next Rank: 10 Posts
Posts: 2
Joined: Wed Jan 23, 2008 3:14 pm
Location: Toronto, ON
by chrishoward76 » Wed Feb 20, 2008 5:59 pm
Hey, just getting my math feet back under me, I am not so bad at exponents, but this question is bugging me. Not sure how I could quickly solve it.
can some one show me a fast way?

(5^21)(4^11)=2x10^n
n=21
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
User avatar
GMAT Instructor
Posts: 3225
Joined: Tue Jan 08, 2008 2:40 pmFollowed by: 614 members
Location: Toronto
Thanked: 1710 times
GMAT Score:800

Re: exponent challenge

by Stuart@KaplanGMAT » Wed Feb 20, 2008 7:08 pm
chrishoward76 wrote:Hey, just getting my math feet back under me, I am not so bad at exponents, but this question is bugging me. Not sure how I could quickly solve it.
can some one show me a fast way?

(5^21)(4^11)=2x10^n
n=21
We see "5" and "4" on the left side and "10" on the right side.. somehow we want to make the bases the same.

So, let's start by turning the "4" into "2^2":

(5^21)((2^2)^11) = 2*10^n

(5^21)(2^22) = 2*10^n

Now, we want to be able to simplify the left side, but we can only do so if the exponents are equal, so:

(5^21)(2^21)(2^1) = 2*10^n

if we divide both sides by 2, we get:

(5^21)(2^21) = 10^n

and since the exponents are equal on the left side, we can say:

(5*2)^21 = 10^21

and finally

10^21 = 10^n

so 21 = n
Image

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

Kaplan Exclusive: The Official Test Day Experience | Ready to Take a Free Practice Test? | Kaplan/Beat the GMAT Member Discount
BTG100 for $100 off a full course
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Newbie | Next Rank: 10 Posts
Posts: 2
Joined: Wed Jan 23, 2008 3:14 pm
Location: Toronto, ON

by chrishoward76 » Wed Feb 20, 2008 7:15 pm
Stuart- thank you very much for that quick response- totally makes sense!
Cheers
Chris
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 231
Joined: Mon Jan 07, 2008 9:39 amFollowed by: 1 member
Thanked: 4 times

by khurram » Sat May 24, 2008 10:09 pm
great explanation Stuart.

Thanks
Khurram
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1